I did the achievement with 3 ranged. I think it was Siege, Rocket, Boulder? It’s a good mix of repositioning and direct damage tools, so it played pretty well. Probably better to swap one of them for Ice with Bethany, though.
I’m only just trying out my first custom squad. I felt like the science mech in the smoke squad wasn’t quite cutting it, so have replaced it with the prime from the rift walkers.
It’s going okay, but I’ve made my first daft move and managed to smoke the terraformer on the desert island which precludes completing one of the objectives.
Artillery might make for an interesting single-class squad. Decent damage and pushing ability, but limited in CQC and possibly awkward for precision strikes.
Like you said, Primes would struggle with board control. Brutes would probably be the worst! Limited board control and poor damage output.
I’ve seen speedruns done with the ice-science mech, so that’s one option?
I unironically love that people are setting challenges for themselves in this game taken straight from the days of Final Fantasy I. Thinking about an all-Brute run just reminds of the people who beat FFI with four White Mages. It really shows how well designed the game is that all these weird combinations are actually viable, if difficult to use.
I tried 3 brutes with Cannon, Jet, Charge (w/ Abe). It didn’t feel terrible, but I think Jet is a bit weak without the Storm Generator, so it would probably be better to take Hook Mech instead, or maybe swap out Charge and take Cannon, Hook, Jet with Kaz.
edit: OK, I tried the second one, and did 3 islands on hard pretty smoothly (spoilers for unlockable dudes)
Picked up an unstable cannon for the hook mech early on, which was really nice. Also got a Phase Cannon and a Targeted Strike for some extra utility.
Oh shit! I totally forgot that I finished it with a three-prime squad: Rift prime, Judoka prime, and Laser prime. The rift and judo primes were excellent for maneuvering bugs around, and with the damage upgrade the laser prime squished everyone left standing.